Want to add a condition to existing reference qualifier on Incident form

[MK_90]

Currently we have below condition on reference qualifier of "configuration Item" field:

javascript:current.service_offering == '' ? 'install_status!=8' : new ServiceOfferingCI().getCi(current)

I want to add a condition to omit the Service Offering Class option from the "Configuration Item" field in the incident form.

How can I combine both the conditions?